ElectroDroid electronic’s calc app

electrodroid
Mats Engstrom writes that he’s had positive experience with the ElectroDroid app. He’s had it installed in his phone for some time now finds it useful. “In addition to a lot of pinouts and lists of nice-to-have info the app also has calculators for Ohm’s law, capacitor charge timings, battery life time, voltage dividers, 555 frequency, LM317 voltage, finding the right resistors to put in series/parallel to get a specific value, and a lot of others. I highly recommend testing the free version which is basically the same as the paid PRO version ($2.49) but with displayed ads.”

Via the contact form.

Workshop Update for January 9th, 2013

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Today we worked on implementing patches to the Bus Pirate that Mrmr was kind enough to contribute in the forum. The two patches fix some issues we had with the frequency measurement function of the Bus Pirate.

The first patch fixes our long integer to string conversion function which added ‘0’ where it shouldn’t have. For example the number 1100000 (1.1M) was converted into 1,0100,000. The patch was applied and tested.

The second patch added a higher resolution method to measuring frequencies lower then 1k. The method uses the input compare hardware peripherals. Unfortunately the V4 and V3 Bus Pirates have different input compare peripherals so some hardware dependent coding was applied. The patch was applied, and is awaiting testing tomorrow.

Both patches were committed to our SVN as of revision 2082. Thanks to Mrmr for his hard work.

We also continued working on the Bus Pirate kit, and have mailed the latest batch of free PCBs.

8 digit 7 segment display with SPI interface

ArduinoSingleModule

Raj designed this 8 digit 7 segment display with an SPI interface using a MAX7219 display driver:

The SPI7SEGDISP8.56 module can be interfaced with any microcontroller that has 3 I/O pins available. If the microcontroller features a built-in hardware SPI, then the display module can be interfaced as a SPI slave device. In that case the SPI signal lines SDO (serial data out), SCLK (serial clock), and SS (slave select) from the microcontroller can be directly connected to the DIN, CLK, and LOAD pins of MAX7219. The LOAD signal is active low.

TI launches real-time operating system

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Texas Instruments has released a free real-time operating system (TI-RTOS) designed for their microcontroller range. They implemented TCP/IP and USB stacks, a FAT file system, and some device drivers.

The TI-RTOS’s source code is released under a license that allows you to use their code as long as you use it on their devices and don’t distribute it. Sounds a lot like the Microchip Application Library license:

…TI hereby grants to you a limited, non-transferable… non-sublicensable…license…for the sole purpose of developing object and executable versions…that execute solely and exclusively on TI Devices, for end use in Licensee Products…

TI used to be one of the better players.

Via Electronics Lab.

DEFCON 20: SIGINT and traffic analysis for the rest of us

At last Summer’s DEFCON 20 conference Sandy Clark and Matt Blaze from the University of Pennsylvania discussed their research into the security of the P25 (APCO Project 25) digital radio protocol. Here they explain the basics of the P25 protocol and examine some of the problems and flaws they uncovered in its security. They highlight passive attacks, where all the attacker needs to do is listen, exploiting usability and key management errors when they occur. They also explain their multi-city networked P25 interception infrastructure which they used to investigate the P25 security protocols in practice.

New QFP prototyping boards tests arrived

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A box of PCBs just arrived from Seeed Studio’s Fusion PCB service, expect them soon in our free PCB drawer. This batch includes:

  • xQFP80 +65 Protoboard
  • xQFP80 +50 Protoboard
  • xQFP50 +65 Protoboard

They are the latest revision of the QFP protoboards already available at Seeed.

Here’s the change list  (QFP protoboard 0.80mm + 0.50mm v2)
-Placed in a standard DP10080 (100 mmx80 mm) PCB
-Added dual QFP pitched footprint back to back to each, each QFP pads were extended for easy soldering
-SSOP32 and SOIC32 pads were also extended
-Added 2 USB footprints, a mini-B and a micro USB, each footprint were placed back to back to each other
-Due to a bigger QFP footprint some component footprint were removed, these are 2 x DO-323, 2 x RC0805, 3 x SOT-23-6

The previous versions of the QFP protoboards are available for $10.

Workshop Update for January 8th, 2013

hilqe

Continued development of Bus Pirate educational kit. We sketched out a few box designs (higher resolution image tweeted), finalized a list of parts to include, and layed out a website.

The Dangerous Prototypes partkit is back on the radar too, we may have a test batch available in a few weeks.

We worked on the Bus Pirate firmware. We are trying to implement a more precise and stable frequency measurement method. The input compare peripheral on the Bus Pirate versions 3 and 4 are slightly different so some hacking is required.

 

DIY solderpaste stencil etching

IMG_2117_v1

Here’s how to etch a solderpaste stencil. The process is similar to the UV photo etching method used for DIY PCBs.

This is all well and good, but commercial stencils are expensive, and are massive overkill for prototype boards. Here is a method for producing a “good-enough” stencil using aluminium sheet via a method similar to PCB production via the UV photosensitive film method.

He also provides a guide on how to use the solderpaste stencil to apply a soldermask to your PCB.

Continue reading “DIY solderpaste stencil etching”

What happens when a V-groove hits your copper pour

IMG_20130102_125150

Panelizing multiple PCBs onto a single panel is a cost effective way of prototyping. V-groves are usually used to separate the different PCBs, making it easy to snap them off. The picture above depicts what happens when the V-grove hits a copper pour such as a ground plane.

Anyway, back to the topic. You usually want to have a copper pour on your boards, be it ground or a power plane. Sometimes it just so happens that you send your Gerbers to the PCB fab but they reply back saying the V-groove will cut the copper, is this OK? Well, in one of my prototype boards I just told them “go ahead”. This is what came back

#FreePCB via Twitter to 2 random RTs

Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters.

Don’t forget there’s free PCBs three times a every week:

  • Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch it every Sunday, right here on the blog
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs will be your friend for the weekend

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Check out how we mail PCBs worldwide video.
  • We’ll contact you via Twitter with a coupon code for the PCB drawer.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.

BP writing U-Boot to TP-Link WR741ND router flash

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Musti is a fan of the Bus Pirate and writes to share his method for using it to unbrick a TP-Link wireless router. The router had been bricked during a failed firmware upgrade, and Musti was able to desolder the FLASH memory chip and rewrite the bootloader to it using BP along with Flashrom.

Get more photos, links and details on Musti’s project on his Wlanslovenija website.

Via the contact form.

PCB a Week 4: RetroTime

RetroTime-gerber1

Mats continues his challenge of designing one PCB every week. In week 4 he came up with RetroTime, a digital clock with RGB LEDs in 12 tentacles extruding from the body of the PCB.

Next week I’ll do a slightly more advanced project than a simple breakout. I had this idea of making a very complex outline on a PCB and see if Seeedstudio and their fab house would accept it. I’m following the series Supernatural where the protagonists often stay at old motels with a lot of 50-60-70’ies decorations and furniture in them, so I decided to to a wall clock with a retro-inspired design.

Via the forum.

Arduino burglary prevention

arduinoTheftBox

michu figures thieves rarely enter a house if they think someone is home. You might fool a burgler by leaving on a light or TV when you go out, but what a waste of electricity. This simple Arduino project simulates the lighting of a TV, making it look like it’s on while consuming far less electricity.

Well I had an old Seee­duino (Atmega 168P) lie around, together with a LiPo Rider Pro and a 6Ah Bat­terie pack. I added two WS2801 LED pix­els and added some lines of Arduino Code — my Arduino Theft Pro­tec­tion was finished.

Via the forum.

A simple, flexible adjustable dummy load

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Nickjohnson posted his flexible dummy load project in the project log forum:

I’ve been testing Loki’s power supply lately, and hurting for the lack of a good dummy load. There are plenty of flexible dummy load projects out there, but they’re largely over-engineered and on the expensive side. I decided to put together a really simple but flexible dummy load.

Via the forum.

Reverse geocaching box

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Brian writes:

I made a single circuit board version of Arduiniana’s famous “Reverse Geocache” box lately. It is based off a PIC instead of an Arduino and incorporates all of the required electronics into one package, saving money and packaging space. The write-up also has a few good tips about the dangers of multiple power supplies, as well as the full code and schematics of the project (including GPS, servo, and LCD libraries for a PIC18).

Via the contact form.

Crystal oscillator frequencies

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Drone refers us to this table of Crystal oscillator frequencies from Wikipedia:

Wikipedia has a nice table of “Crystal oscillator frequencies”. The table includes a column of crystals divisible by powers of 2 which may be appropriate for Real Time Clock (RTC) references…

Xtal frequencies covered in the table (at my post-time) cover 32768KHz through 161.1328MHz. Typical applications for a specific frequency are also covered. Worth a look.

Via the contact form.

ATX Breakout Board V1.1 Acrylic case V1 back in stock at Seeed

ATXBreakout Board case-W600

The ATX Breakout Board v1.1 Sick of Beige case is back in stock at Seeed Studio.  This case is designed to be simple, cheap, and easy to assemble. The ATX Breakout Board is  sandwiched between two laser-cut acrylic sheets, and the whole assembly is held together with aluminum screws and standoffs.

This is a minor update with the secondary ground and -5volt post holes cut, and a ventilation opening over the big resistor.

Check out our tutorial on how to customize Sick of Beige cases.

You can get one for $4 at Seeed Studio.

ENC424J600 breakout free PCB build

A_5P8b8CIAA2118-W600

Garyservin built a free ENC424J600 Ethernet breakout board. This is the 100MBPS ethernet chip from Microchip, the fairly recent update to the 10MBPS ENC28J60.

If you build a free PCB we’ll send you another one! Blog about it, post a picture on Flicker, whatever – we’ll send you a coupon code for the free PCB drawer.

Via the forum.

Free TI breakout boards

OPA_SO_1A_t
Goran provided this quick tip: “TI has some free breakout boards right now – even shipping is zero cost.” Check the TI estore for details and availability.

TI says the board involved is “the DEM-OPA-SO-1A demonstration fixture helps designers evaluate the operation and performance of TI’s High Speed, Wide Bandwidth Operational Amplifiers. This unpopulated PC board is compatible with products offered in the 8-lead SOIC (D) package.”

Via the contact form.